This invention relates generally to catheters for coronary arteries and more particularly to a steerable catheter that has a distal segment to abut an inside surface of an ascending aorta and that also has a three dimensional distal portion to facilitate entry of a distal tip into the ostium of a right coronary artery extending from the ascending aorta such that the catheter is adequately supported for subsequent procedures.
The use of catheters in diagnosing and treating vessels in a human body is well known. One particular known therapeutic use of catheters is in performing percutaneous transluminal coronary angioplasty (PTCA). One technique for performing PTCA in a right coronary artery includes inserting a guide catheter into a femoral artery and advancing the guide catheter such that its distal tip moves through that artery, up the descending aorta, and ultimately into the ostium of the right coronary artery. A balloon catheter may then be pushed through the guide catheter into the right coronary artery to perform medical procedures in known manner. As an example of a diagnostic use, a diagnostic catheter can be similarly placed and then used to conduct a radiopaque dye injected in known manner. The main difference between a guide catheter and a diagnostic catheter is that the lumen is typically larger in a guide catheter to accommodate various tools and instruments that are pushed through the lumen.
Catheter terminology has not be consistently used or adopted by the medical profession or by medical publications. Accordingly, for definitional purposes herein, catheters for the right coronary artery can be divided into two functional categories: the “completely preformed catheter” and the “steerable catheter”. Both types have a preformed tip designed to be positioned in the ostium of the right coronary artery. The completely preformed catheter, known by some as a non-torqueable catheter, is designed such that the preformed tip can be positioned in the ostium of the right coronary artery simply by advancing the catheter to the proper level, without manipulating or torquing (twisting) the catheter. Completely preformed catheters generally require a lower degree of skill to position the tip in the ostium of the right coronary artery; however, they do not always work well for all patients due to different morphologies among patients.
The second type of catheter for the right coronary artery is the “steerable catheter”. A steerable catheter, known by some as a partially preformed catheter or a torquable catheter, can be torqued (twisted) to steer the catheter to the desired location. The proximal end of the catheter is torqued, typically in a clockwise direction, which causes the distal end of the catheter to also twist and be steered into the ostium of the right coronary artery. Steerable catheters require a greater degree of skill, but work with a greater variety of morphologies. Steerable catheters (and fully preformed catheters) can be used for both therapeutic and diagnostic purposes and thus include both guide and diagnostic catheters. In other words, “steerable catheter” as used herein includes the subclasses of both guide and diagnostic catheters.
There are no known three-dimensioned steerable guide catheters in the marketplace. The VR (Voda Right) catheter available from Scimed Life Systems, Inc. is three-dimensional and is a guide-type catheter, but it is not steerable. The Williams catheter also available from Scimed Life Systems, Inc. is a three-dimensional steerable catheter, but it is a diagnostic catheter and not a guide catheter.
Thus, there are known types of catheters designed for the right coronary artery. However, there remains the need for a new type of steerable catheter that can be readily used with different right coronary artery morphologies found in patients. There is also a need for a steerable catheter, especially of the guide type, that can be better controlled and that has a distal end that is better supported and more stable when the tip is positioned in the ostium of the right coronary artery so the forces exerted by pushing tools and instruments through the lumen of the catheter do not cause the tip to move or become dislodged from the ostium of the right coronary artery. There is the particular need for a steerable catheter which has a preformed three-dimensional distal end portion having a tip and shaped such that the tip readily enters the ostium of the right coronary artery upon the placement of the catheter or when suitable torque is applied to the proximal end of the catheter and such that the distal end portion is adequately supported for subsequent procedures. Such need is intended to be satisfied pursuant to the disclosure in my U.S. Pat. No. 6,595,983; however, an improvement on my prior invention has been invented as described below.